Corneas and scleras derive their structural strength, shape and integrity from collagen. The strength of the intertwined collagen strands is a function of covalent cross-links established between and within collagen strands and between collagen and glycoproteins in the matrix. In structurally robust corneas and scleras, an enzyme called lysyl oxidase performs the collagen cross-linking function in a process called oxidative deamination using molecular oxygen present in the tissue. The biomechanical strength of corneal and scleral collagen can be reduced by a number of conditions including iatrogenic effect from surgical intervention, prosthesis, or medications, or the cause of corneal or scleral weakness can be congenital, idiopathic or due to microbial causes or trauma. In these cases of corneal or scleral weakness, interventional strategies to strengthen the collagen or to reduce infections are often employed.